PostgreSQL aggregate views

Are views in PostgreSQL completely recalculated every time one of underneath tables are changed?

More precisely, if I have aggregate view over table votes, will complete recalculati开发者_运维技巧on of a view be needed, when any changes are made in votes table?

If I expect often changes of votes table, what are alternatives to aggregate view? I need polylogarithmic time complexity of simple querys.

Normal VIEWS in Postgres (and other RDBMS's that I'm aware of) are really nothing more than a stored SELECT statement. Its not storing the actual information in a static table - thats a materialized VIEW (which Postgres doesn't currently have, and you'll have to roll your own). It will in a sense "recalculate every time", in that it doesn't store the calculated data.

Check the previous link for how to do a materialized view if you want to store the complex calculations.

EDIT: If like OMG Ponies says, you're talking about ALTER TABLE on the underlying table - then its easy...Postgres won't let you change the definition of a column that used in a VIEW without dropping the VIEW first.

You could use PostgreSQL's Materialized views.

Materialized views are certainly possible in PostgreSQL. Because of PostgreSQL's powerful PL/pgSQL language, and the functional trigger system, materialized views are somewhat easy to implement. I will examine several methods of implementing materialized views in PostgreSQL.

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